Oral Corticosteroids Can Lead to Vitamin D Deficiency

People taking the powerful drugs should have blood levels tested.

| By Otesa Middleton Miles

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People who take oral corticosteroids for arthritis and other illnesses are twice as likely as non-users to have a vitamin D deficiency, according to research from Albert Einstein College of Medicine of Yeshiva University, in New York City. The finding raises the issue of who should be tested for low vitamin D levels and how often.

Corticosteroids, including prednisone, are a class of powerful drugs that reduce inflammation and suppress the immune system. They are prescribed for a wide variety of conditions, including rheumatoid arthritis (RA) and lupus, as well as multiple sclerosis, some types of cancer, asthma and skin rashes – including those caused by poison ivy. They can be prescribed short-term – until a rash clears up or until another drug can take effect, for example – or they may be used long-term. Corticosteroids come in skin creams, injections and inhaled forms; however, this study examined only people who took them orally.

The cross-sectional study, published in The Journal of Clinical Endocrinology and Metabolism, reviewed data from more than 22,500 Americans of all ages. Of those, 181 had used oral corticosteroids in the previous 30 days. Eleven percent of oral corticosteroid users had a “severe” vitamin D deficiency compared with 5 percent of those who hadn’t taken oral corticosteroids in the previous 30 days.

The lead author of the study recommends testing vitamin D levels before and during treatment for patients on oral corticosteroids. “Patients should ask their doctors about their vitamin D levels, especially patients who are on steroids,” says Amy Skversky, MD, an assistant professor of pediatrics at Einstein and Montefiore Medical Center, also in New York. She encourages continuous vitamin D monitoring among long-term users because they may be at an even higher risk of vitamin D deficiency.

The body needs vitamin D to absorb calcium, which is crucial for maintaining strong bones and staving off osteoporosis. Vitamin D, which the body produces when the skin is exposed to sunlight, also is believed to help lower inflammation. There also is evidence that vitamin D protects the body from a host of ailments including diabetes, high blood pressure and some cancers.

The U.S. Food and Drug Administration’s latest guidelines recommend people ages 1 to 70 get 600 international units of vitamin D per day, and people older than 70 get 800 IUs a day. Many experts say adults can tolerate more vitamin D without much danger – up to 4,000 international units – although there is debate about how much is too much. Extremely high doses of vitamin D supplements can cause constipation, bone damage, kidney stones and other conditions.

The American College of Rheumatology (ACR) recommends that patients take vitamin D and calcium supplements if they take any dose of corticosteroids, also called glucocorticoids. And although there are no firm guidelines in place, the ACR also tells doctors to consider annual vitamin D testing for patients on corticosteroids for more than three months.

Some doctors already make a habit of checking vitamin D levels before patients start corticosteroids. Stanley Cohen, MD, a practicing rheumatologist and a clinical professor in the department of internal medicine at the University of Texas Southwestern Medical School, began testing his patients' vitamin D levels more than three years ago when he saw several surveys that suggested vitamin D deficiency might be prevalent among these patients.

Dr. Cohen sees almost 90 patients each week; roughly 20 to 30 percent of them are taking oral steroids. “We find low vitamin D levels quite frequently. In about 30 to 40 percent of the patients we test, the vitamin D levels are low and we have to treat them,” he says. Most patients can get their levels back to normal with an over-the-counter supplement, he notes, but if they are severely vitamin-D deficient, prescription-strength doses are needed.

Dr. Cohen says this new research further confirms the need to regularly check patients’ vitamin D levels. “We already knew that people on corticosteroids are at a higher risk for fractures,” he says. “This is another thing we need to be aware of. It’s very easy to treat this by monitoring vitamin D levels and replacing vitamin D.”

Indeed, a known downside of corticosteroids is that they increase the risk of fractures via a mechanism other than vitamin D deficiency. By decreasing the amount of calcium the body can absorb and increasing the amount of calcium that is excreted from the body, corticosteroids decrease bone formation and increase bone loss. Experts, however, aren’t certain why corticosteroids impact vitamin D levels.